The proposed research involves the study of the control of tRNA methyltransferase activity in a variety of normal tissues and tumors through its interaction with competing enzyme systems and naturally occurring inhibitors, such as S-adenosylhomocysteine. Some of the systems to be studied include normal adult liver vs. foetal liver and hepatomas; an organ under hormonal control, the uterus in the normal and ovariectomized state; and a number of cell lines in tissue culture, normal, tumor-derived and virally transformed lines. The consequences of the inhibitory control in normal tissue and its absence in tumor tissue will be examined in an attempt to correlate this with neoplastic aberrations such as uncontrolled growth or expression of foetal antigens. A variety of enzymatic and immunologic techniques will be used.